Functional fiber and manufacturing method thereof

ABSTRACT

A functional fiber which, over long periods of time, can maintain excellent heat retention and deodorant antibacterial properties without reducing moisture absorption and desorption, and which moreover can be obtained efficiently, and a manufacturing method of said fiber are provided. This functional fiber has a fiber material imparted with an infrared radiation function and a deodorant antibacterial function. A silicone elastomer film that contains aluminum oxide particles with an average particle diameter of 1-10 μm is fixed to at least part of the surface of the fiber material. The silicone elastomer film has polyoxyethylene alkyl ethers of 12-15 carbons as the main component, and has a siloxane backbone.

TECHNICAL FIELD

The present invention relates to a functional fiber imparted with an infrared radiation function and a deodorizing and antibacterial function, as well as to a method for manufacturing such a functional fiber.

BACKGROUND ART

As methods for enhancing a heat retention property of a fiber material, there are known to utilize moisture absorbing and heat producing fibers which absorb moisture and generate heat (see, for example, Japanese Laid-Open Patent Publication No. 2014-009408), and to form a heat insulating layer that contains air by raising the nap of a fiber material, or by interposing feathers or the like between such fiber materials (see, for example, Japanese Laid-Open Patent Publication No. 2013-177721).

SUMMARY OF INVENTION

However, even when moisture absorbing and heat producing fibers are used, in the case that moisture absorption by the fibers becomes saturated, generation of heat no longer occurs, and thus the ability to sustain heat generation is low. Further, for example, in the case that moisture absorbing and heat producing fibers are used for clothing, there is a concern that moisture adsorbed on the surface of the fibers will not undergo desorption, and stuffiness or mugginess may occur, thus causing discomfort to the wearer. Furthermore, there is a concern that the moisture adsorbed by the fibers may become frozen, and therefore such fibers are not suitable for use in extremely cold places.

In the case of forming a heat insulating layer by brushing up or raising the nap of the fiber material, since the raised fibers are liable to fall off from the fiber material by washing or the like, it is difficult to enhance heat retention over a long period. In addition, the formation of a heat insulating layer by feathers or the like has a problem in that the fiber material becomes bulky and it becomes difficult to wash such a material at home.

Further, in recent years, together with improving the heat retention property of a fiber material, it has been desired to obtain a functional fiber endowed with a deodorizing and antibacterial function. However, in this case, apart from the methods of improving heat retention as described above, it is necessary to perform a treatment to impart such a deodorizing and antibacterial function. Therefore, there is a concern that the manufacturing process for the functional fiber may become complicated.

The present invention has been devised taking into consideration the aforementioned problems, and has the object of providing a functional fiber and a method of manufacturing the same, in which it is possible to maintain superior heat retention and a deodorizing and antibacterial property over a prolonged period without lowering the moisture absorption/desorption property thereof.

In order to achieve the above-described object, the present invention is characterized by a functional fiber having a fiber material imparted with an infrared radiation function and a deodorizing and antibacterial function, wherein a silicone elastomer film containing aluminum oxide particles having an average particle diameter of 1 to 10 μm is affixed to at least a portion of the surface of the fiber material, and the silicone elastomer film contains as a principal component thereof polyoxyethylene alkyl ether having 12 to 15 carbon atoms, and has a siloxane skeleton.

The aluminum oxide particles carry out absorption and reemission particularly favorably in a range of 8 to 14 μm from among the infrared rays (3 to 50 μm) irradiated from the human body. Stated otherwise, the aluminum oxide particles have an infrared radiation function that generates heat by efficiently utilizing the heat rays irradiated from the human body or another heat source. Further, the aluminum oxide particles have a deodorizing function with respect to ammonia, isovaleric acid, and nonenal, and the like, which cause offensive odors, and have an antibacterial function with respect to staphylococcus aureus, moraxella osloensis, pseudomonas aeruginosa, and the like. Accordingly, by providing the functional fiber according to the present invention with the aluminum oxide particles, the infrared radiation function is imparted thereto together with imparting the deodorizing and antibacterial function, and therefore, it is unnecessary to impart such functions separately, and by this measure, the functional fiber can be obtained in an efficient manner.

Further, by setting the average particle diameter of the aluminum oxide particles to lie within the above-described range, it is possible to avoid a deterioration in the flexibility and the texture and feel of the fiber material, even if the aluminum oxide particles are affixed to the fiber material. Even if such aluminum oxide particles are affixed to the surface of the fiber material by the above-described silicone elastomer film, the bulkiness of the fiber material is not increased, and the moisture absorption/desorption property does not decrease.

Furthermore, since the silicone elastomer film can freely expand and contract in following relation with deformation of the fiber material, it is possible to maintain the state in which the silicone elastomer film is firmly affixed to the surface of the fiber material. Accordingly, even in the case that a frictional force or the like is applied to the fiber material while placed in water or in a chemical cleaning agent at a time of washing, it is possible to prevent the silicone elastomer from peeling off from the surface of the fiber material. Since aluminum oxide particles are contained in the silicone elastomer film which is firmly affixed to the fiber material in this manner, a reduction in the aforementioned functions added by the aluminum oxide particles due to washing of the functional fiber or the like can be suppressed, and the sustainability of such functions is superior.

As described above, while providing a sufficient moisture absorption/desorption property, the functional fiber is capable of maintaining superior heat retention and a deodorizing and antibacterial property over a prolonged period, and can be obtained in an efficient manner.

Further, the present invention is characterized by a method of manufacturing a functional fiber having a fiber material imparted with an infrared radiation function and a deodorizing and antibacterial function, comprising the steps of immersing the fiber material in an aqueous dispersion liquid in which there are dispersed silicone elastomer particles containing as a principal component thereof polyoxyethylene alkyl ether having 12 to 15 carbon atoms, and having a siloxane skeleton, and aluminum oxide particles having an average particle diameter of 1 to 10 μm, and by a heating treatment, affixing to at least a portion of the surface of the fiber material the silicone elastomer in the form of a film in which the silicone elastomer particles are crosslinked, and containing the aluminum oxide particles.

Through the above process steps, the functional fiber can be obtained in an efficient manner, and possesses a superior heat retention property obtained by efficiently utilizing heat rays irradiated from the human body or another heat source to generate heat, together with a deodorizing property with respect to ammonia, isovaleric acid, nonenal, and the like, and an antibacterial property with respect to staphylococcus aureus, moraxella osloensis, pseudomonas aeruginosa, and the like.

Further, even if aluminum oxide particles having an average particle size lying within the above-described range are affixed to the fiber material by the aforementioned silicone elastomer film, lowering of the flexibility and texture and feel of the fiber material, an increase in the bulkiness of the fiber material, and a deterioration in the moisture absorption/desorption property can be suppressed. Furthermore, since the aluminum oxide particles are contained in the silicone elastomer film which is firmly affixed to the fiber material in this manner, the sustainability of the aforementioned functions added by the aluminum oxide particles is excellent.

According to the present invention, it is possible to efficiently obtain a functional fiber which, while providing a sufficient moisture absorption/desorption property, is capable of maintaining superior heat retention and a deodorizing and antibacterial property over a prolonged period.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram of a measurement apparatus for performing an infrared radiation function test.

DESCRIPTION OF EMBODIMENTS

A preferred embodiment of a functional fiber according to the present invention will be presented and described in detail below in relation to a manufacturing method for manufacturing the same.

As will be described later, the functional fiber according to the present invention includes a fiber material which is imparted with an infrared radiation function and a deodorizing and antibacterial function. The type of fiber material is not particularly limited, and may contain only natural fibers, only synthetic fibers, or both of such fibers.

The natural fibers may contain only cellulose fibers, only animal fibers, or both of such fibers. As representative cellulose fibers, there may be cited cotton which is a natural plant fiber, but the cellulose fibers may also be hemp fibers such as ramie, linen, hemp, jute, manila hemp, sisal hemp, or the like. Further, the cellulose fibers may be composed of so-called regenerated fibers obtained by dissolving natural cellulose in a predetermined solvent and then molding it into a fibrous form. Specific examples of this type of regenerated fiber include rayon, polynosic, cupra, and Tencel (registered trademark of Lenzing AG, Austria).

Representative examples of animal fibers include silk, wool, or animal hair fibers. Specific examples of animal hair fibers include alpaca, mohair, angora, cashmere, camel, vicugna, and the like.

Examples of synthetic fibers include polyester, acrylic, polyurethane, aliphatic polyamide-based fibers (including 6-nylon and 6,6-nylon), aromatic polyamide-based fibers, and the like.

The form of the fiber material is not particularly limited, and examples thereof may include cotton ball, tow, filaments, slivers, yarn, a non-woven fabric, a woven fabric, a knitted fabric, a towel, paper, or the like.

The ratio of the cellulose fibers, the animal fibers, and the synthetic fibers in the fiber material is not particularly limited, and can be set to any desired ratio.

In the functional fiber, a silicone elastomer film containing aluminum oxide particles having an average particle size of 1 to 10 μm is affixed to at least a portion of the surface of the fiber material. The average particle diameter can be measured with a commercially available particle size analyzer or the like, and for example, can be set to a particle diameter at an integrated value of 50% (D50) in a particle size distribution obtained by a laser diffraction/scattering method.

The aluminum oxide particles carry out absorption and reemission particularly favorably in a range of 8 to 14 μm from among the infrared rays (3 to 50 μm) irradiated from the human body. Stated otherwise, the aluminum oxide particles have an infrared radiation function that generates heat by efficiently utilizing the heat rays irradiated from the human body or another heat source. Further, the aluminum oxide particles have a deodorizing function with respect to ammonia, isovaleric acid, and nonenal, and the like, which cause offensive odors, and have an antibacterial function with respect to staphylococcus aureus, moraxella osloensis, pseudomonas aeruginosa, and the like.

The silicone elastomer film contains as a principal component thereof polyoxyethylene alkyl ether having 12 to 15 carbon atoms, and has a siloxane skeleton. More specifically, the silicone elastomer film is a porous film having a plurality of micropores, and the surface of the film has a scale-like shape. The silicone elastomer film is affixed to the surface of the fiber material mainly by a mechanical action such as an anchor effect or the like.

Next, a process of obtaining the functional fiber which is configured basically in the manner described above will be described in relation to a manufacturing method according to the present embodiment.

First, silicone elastomer particles, which contain as a principal component thereof polyoxyethylene alkyl ether having 12 to 15 carbon atoms, and having a siloxane skeleton, are dispersed in an aqueous dispersion medium such as water to thereby prepare an aqueous dispersion liquid. Such an aqueous dispersion liquid can be obtained by mixing a commercially available product such as “X-51-1318” (trade name) (a silicon emulsion manufactured by Shin-Etsu Chemical Co., Ltd.), and a commercially available product such as “KB-ASN” (trade name) (a 20% dispersion of aluminum oxide particles manufactured by Satoda Chemical Industrial Co., Ltd.), which are prepared to an appropriate concentration.

After the fiber material is immersed in the thus prepared aqueous dispersion liquid, the liquid is wrung out from the fiber material. Thereafter, the silicone elastomer particles are crosslinked by carrying out a heating treatment with respect to the fiber material on which a drying treatment was performed. Consequently, a silicone elastomer film containing aluminum oxide particles is formed, and the film can be firmly affixed to the surface of the fiber material primarily by an anchor effect.

The heating treatment can be carried out using existing heating equipment such as a heat setter, for example. However, it is preferable to carry out the heat treatment by steam setting using water vapor. In this case, for example, saturated steam at 100° C. or less is used in order to crosslink the silicone elastomer particles, and therefore, it becomes possible to obtain a functional fiber that exhibits further enhanced flexibility. Further, since the saturated steam is capable of entering, for example, even into gaps between superimposed fiber materials, it is possible to effectively supply heat to the entirety of the fiber materials without bias.

Therefore, carrying out steam setting is particularly preferred in the case that the fiber material is formed by filaments. More specifically, even in the case that a heating treatment is performed in a state in which fiber filaments are wound up together, heat can be spread by saturated steam to the fiber material on an inner side of the windings, thereby enabling the silicone elastomer film to be formed.

Further, in the case of performing steam setting, generation of active oxygen or the like can be suppressed by filling the surrounding environment of the fiber material with saturated steam. Consequently, it becomes possible to obtain a functional fiber in which damage or embrittlement due to the influence of active oxygen is suitably avoided.

The functional fiber may be constituted solely from a fiber material to which the silicone elastomer film containing the aluminum oxide particles is affixed in the manner described above, or the functional fiber may be constituted by combining the fiber material together with other fibers.

With the functional fiber which is obtained by way of the above-described process, the provision of aluminum oxide particles imparts an infrared radiation function together with a deodorizing and antibacterial function. Stated otherwise, there is no need for the infrared radiation function and the deodorizing and antibacterial function to be imparted separately, and by this measure, the functional fiber can be obtained in an efficient manner.

Further, by setting the average particle diameter of the aluminum oxide particles to lie within the above-described range, it is possible to avoid a deterioration in the flexibility and the texture and feel of the fiber material, even if the aluminum oxide particles are affixed to the fiber material. Further, even if such aluminum oxide particles are affixed to the surface of the fiber material by the above-described silicone elastomer film, an increase in the bulkiness of the fiber material, and a reduction in the moisture absorption/desorption property can be suppressed.

Furthermore, since the silicone elastomer film can freely expand and contract in following relation with deformation of the fiber material, it is possible to maintain the state in which the silicone elastomer film is firmly affixed to the surface of the fiber material. Accordingly, even in the case that a frictional force or the like is applied to the fiber material while placed in water or in a chemical cleaning agent at a time of washing, it is possible to prevent the silicone elastomer from peeling off from the surface of the fiber material. Since aluminum oxide particles are contained in the silicone elastomer film which is firmly affixed to the fiber material in this manner, a reduction in the aforementioned functions added by the aluminum oxide particles due to washing of the functional fiber or the like can be suppressed, and the sustainability of such functions is superior.

As described above, with such a functional fiber, it is possible to maintain excellent heat retention and a deodorizing and antibacterial property over a prolonged period, and the functional fiber can be obtained in an efficient manner.

Further, as described above, the silicone elastomer film is affixed to the surface of the fiber material mainly by a mechanical action such as an anchor effect or the like. Therefore, for example, in the case that the fiber material is a natural fiber, the majority of the functional groups in the natural fiber exist in a state in which chemical bonds such as covalent bonding are not formed with the silicone elastomer film. Therefore, when the functional fiber is dyed, the functional groups in the natural fiber and the dye are capable of reacting sufficiently with each other, and dying with the dye can be performed suitably while avoiding color unevenness. Further, even in the event that frictional forces or the like are applied to hydrophobic fibers in water or in a chemical cleaning agent when dyeing is performed, it is possible to prevent the silicone elastomer film from peeling off from the surface of the natural fibers.

Stated otherwise, if the functional fiber includes a fiber material made of natural fibers, the functional fiber is excellent in terms of its ability to be dyed, and piece dyeing thereof can be performed easily. As a result, it is possible to stock the functional fiber in an undyed and unsewn condition, to carry out dying on the basis of information of fashionable colors collected immediately prior to sale thereof, and to directly perform sewing or the like thereon to quickly result in a textile product. Therefore, it is possible to provide commercial products in which rapidly changing fashionable colors and patterns are accurately captured in a short delivery period, and to reduce defective inventory and make effective use of resources, and hence, to reduce the cost of sewn products in which the functional fiber is used.

Although a preferred embodiment of the present invention has been described above, the present invention is not limited to the present embodiment, and various changes and modifications may be adopted therein without departing from the scope of the invention.

Examples

Hereinafter, the present invention will be described in detail with reference to various examples thereof. However, the present invention is not limited to such examples.

A description will be given concerning examples of functional fibers obtained by forming the silicone elastomer film containing aluminum oxide particles on the following fiber materials.

A fiber material made from a material A of 100% cotton was used in the states of a woven fabric A1 and a knitted fabric A2. The woven fabric A1 was a satin fabric containing 173 warp yarns per inch prepared using No. 60 single yarn, and containing 84 weft yarns per inch prepared using No. 40 single yarn. The knitted fabric A2 was a circular rib fabric prepared using No. 40 single yarn at 18-gauge, 30 inches.

A fiber material made from a material B was prepared by blending cotton and Tencel at a ratio of 80 to 20 in the state of a knitted fabric B1. The knitted fabric B1 was a circular rib fabric prepared using No. 40 single yarn at 19-gauge, 18 inches.

Among the fiber materials, initially, desizing, scouring, and bleaching were carried out on the woven fabric A1. Further, initially, desizing, scouring, bleaching, dehydration, and drying were carried out respectively on the knitted fabrics A2 and B1.

Next, after immersing the aforementioned fiber materials respectively in an aqueous dispersion liquid prepared so as to contain 30 g/L of the above-described “X-51-1318” and 50 g/L of the above-described “KB-ASN”, the liquid was wrung out from the fiber materials. As a result, a ratio (wringing ratio) of the weight of the attached aqueous dispersion liquid to the weight of the fiber material before immersion was set to 70%. The fiber materials were subjected to a drying treatment at 150° C. for one minute and thirty seconds using a heat setter manufactured by IL SUNG MACHINERY, Co., Ltd.

Next, among the fiber materials after implementation of the drying treatment thereon, the woven fabric A1 was subjected to a heat treatment at 170° C. for two minutes using a baking machine manufactured by SANDO ENGINEERING Co., Ltd., and thereafter, was subjected to a shrink-proofing process in order to obtain a functional fiber. On the other hand, concerning the knitted fabrics A2 and B1, a heat treatment was carried out thereon at 170° C. for two minutes using the above heat setter in order to obtain functional fibers.

The functional fibers which were obtained in the foregoing manner were used as inventive examples. On the other hand, fiber materials which did not include the above-described silicone elastomer film containing aluminum oxide particles were used as comparative examples.

(Infrared Radiation Function)

In relation to the fiber materials (functional fibers) A1, A2, and B1 according to the above-described inventive examples and the fiber materials A1, A2, and B1 according to the comparative examples, an infrared radiation functional test was conducted using the measurement apparatus 10 shown in FIG. 1. The measurement apparatus 10 includes a first water tank 12, a heater 14, a second water tank 16, a container 18, and a thermography device 20. A heater 14 is disposed inside the first water tank 12, and by operation of the heater 14, the temperature of the hot water stored in the first water tank 12 is maintained within a range of 35° C. to 38° C. corresponding to human body temperature.

The second water tank 16 is disposed in the first water tank 12 in a manner so that the surrounding periphery of an opening thereof protrudes from the water surface of the first water tank 12. As a result, the hot water stored inside the second water tank 16 is maintained at the same temperature as the hot water stored inside the first water tank 12.

The container 18 is made of stainless steel (SUS 430, SUS 410) and is disposed to float on the water surface of the second water tank 16. A polyester material 22 is affixed to an inner bottom surface of the container 18, and a test specimen 24 of the fiber material according to the inventive example and a test specimen 26 of the fiber material according to the comparative example are placed on the material 22. By interposing the material 22 between the bottom surface of the container 18 and the test specimens 24 and 26 in this manner, heat can be transferred uniformly from the hot water stored inside the second water tank 16 to the test specimens 24 and 26.

The thermography device 20 includes an infrared camera disposed in opposition to the test specimens 24 and 26 that are set inside the container 18 from an opposite side of the material 22, and is capable of measuring at predetermined time intervals changes in temperature of the test specimens 24 and 26. For the thermography device 20, model number “FLIR E60” manufactured by FLIR Systems Japan Inc. was used.

Using the measurement apparatus 10, the temperature (X) of the test specimen 24 according to the inventive example, the temperature (Y) of the test specimen 26 according to the comparative example, and the surface temperature of the hot water in the second water tank 16 were measured respectively. In Table 1, there are shown the measurement results, and the difference (X−Y) as calculated from the measurement results, between the temperature (X) of the test specimen 24 according to the inventive example and the temperature (Y) of the test specimen 26 according to the comparative example.

TABLE 1 Heating Infrared Radiation Function(° C.) Time Comparative Heated Water Period Example Example Difference Surface (minutes) (X) (Y) (X − Y) Temperature A1 10 35.7 35.2 0.5 37.8 20 34.4 33.9 0.5 36.9 30 34.5 34.1 0.4 37.2 60 34.8 34.3 0.5 37.1 90 34.9 34.4 0.5 36.5 120 33.4 32.7 0.7 35.6 A2 10 36.0 35.2 0.8 40.0 20 37.2 36.8 0.4 40.0 30 34.2 33.4 0.8 39.0 40 34.0 33.6 0.4 37.0 50 34.2 33.6 0.6 37.3 60 33.8 33.3 0.5 36.8 70 33.8 33.5 0.3 36.8 80 33.5 33.0 0.5 37.0 90 33.9 33.5 0.4 36.5 120 33.3 32.8 0.5 36.2 480 32.9 32.5 0.4 36.6 B1 10 35.1 34.4 0.7 37.5 20 35.2 34.8 0.4 37.6 30 34.3 33.9 0.4 36.8 60 34.3 33.7 0.6 36.7 90 34.3 33.8 0.5 36.8 120 33.8 33.4 0.4 36.2 180 35.0 34.5 0.5 27.4 240 34.7 34.1 0.6 36.9

From Table 1, it can be understood that, at any of the heating time periods, all of the test specimens 24 according to the inventive examples exhibit higher temperatures than the test specimens 26 according to the comparative examples. Therefore, the functional fiber according to the present embodiment exhibits excellent heat retention by absorption and reemission of infrared rays having the same wavelength as infrared rays irradiated from the human body.

(Deodorizing Property)

With respect to the test specimen B1 according to the inventive example, the deodorizing property with respect to ammonia, isovaleric acid, and nonenal was evaluated. With respect to ammonia, the deodorizing property was measured in the following manner in accordance with an instrumental analysis (detection tube method) prescribed by the general incorporated association of the Japan Textile Technology Council. The following measurements were performed on both the test specimen before washing and the test specimen after washing 100 times according to the above-described washing method.

First, 2.4 g of the test piece was placed in a 5 L Tedlar bag and was tightly sealed therein. Next, using a syringe, 3 L of an odor component gas was injected into the Tedlar bag so as to obtain a prescribed initial concentration. Two hours after injection of the odor component gas, the concentration of the odor component gas in the Tedlar bag was measured with the detector tube. A similar test (blank test) was performed except that the test specimen was not inserted into the Tedlar bag, and the rate of decrease in the odor component was determined using the following equation (1). The initial concentration of ammonia was 100 ppm.

Reduction Rate (%)={(Measured Value in Blank Test After Two Hours−Measured Value of Test Specimen After Two Hours/Measured Value in Blank Test After Two Hours)}×100   (1)

The deodorizing property with respect to isovaleric acid and nonenal was evaluated in the following manner according to a gas chromatography method prescribed by the general incorporated association of the Japan Textile Technology Council. 1.2 g of each test specimen was placed in a 500 mL Erlenmeyer flask, an ethanol solution of an odor component was added thereto in a dropwise manner so as to obtain a prescribed initial concentration, and the flask was sealed. Two hours later, sampling was performed with a syringe, and the concentration of the odor component was measured by gas chromatography. A similar test (blank test) was performed except that the test specimen was not inserted into the Erlenmeyer flask, and the rate of decrease in the odor component was determined using the above equation (1). The initial concentrations of isovaleric acid and nonenal were about 14 ppm and 4 ppm, respectively.

The test results are shown in Table 2.

TABLE 2 Reduction Rate (%) Ammonia Isovaleric Acid Nonenal B1 Washing 0 99.0 ≥99.0 81.0 (times) 100 84.0 ≥99.0 72.0

From Table 2, it can be understood that the functional fiber according to the present embodiment exhibits a sufficient deodorizing property with respect to any of the odor components of ammonia, isovaleric acid, and nonenal. Further, it can be understood that the functional fiber can sufficiently maintain the deodorizing property even after having been washed 100 times, and that a superior deodorizing property is sustained.

(Antibacterial Property)

In relation to the test specimen B1 according to the inventive example, an antibacterial property with respect to staphylococcus aureus, pseudomonas aeruginosa, and moraxella osloensis was evaluated. More specifically, in this evaluation, bactericidal activity values were measured by a 10.1 bacterial suspension absorption method as defined in “Testing for antibacterial activity and efficacy on textile products” of JIS L 1902:2008. The measurements were performed on both the test specimen before washing and the test specimen after washing 100 times according to the above-described washing method. Measurement results concerning bactericidal activity values are shown in Table 3. Moreover, when the bactericidal activity values were zero or greater, the test specimen was considered to have a bacteriostatic effect.

TABLE 3 Antibacterial Property (Bacteriostatic Activity Value) Staphylococcus Pseudomonas Moraxella aureus aeruginosa osloensis B1 Washing 0 ≥3.1 ≥3.0 ≥3.0 (times) 100 ≥3.1 1.2 1.6

From Table 3, it can be understood that, with the functional fiber according to the present embodiment, a bactericidal activity value of zero or greater was exhibited, and the bactericidal activity value could be maintained within the aforementioned range even after having been washed 100 times. Stated otherwise, the functional fiber exhibits a superior antibacterial property, and such an antibacterial property can be continuously obtained.

(Moisture Absorption/Desorption Property)

Concerning the test specimen B1 from among the fiber materials according to the inventive example and the comparative example, the moisture absorption/desorption property (moisture content ratio) thereof was evaluated in accordance with the Boken method by the general incorporated association of the Boken Quality Evaluation Institute. More specifically, first, a test specimen of the aforementioned fiber material having a size of 20 cm² was exposed to an environment of 40° C. and 90% (RH) for 4 hours, whereby moisture was absorbed into the test specimen. Thereafter, moisture was released from the test specimen by exposing the test specimen for 4 hours under an environment of 20° C.×65% (RH). At this time, the weight (g) of the test specimen was measured with each elapse of one hour, and the moisture absorption/desorption property (moisture content ratio) (%) was obtained from such a change in weight. The results thereof are shown in Table 4. The environment of 40° C.×90% (RH) is a high temperature high humidity state which approximates the temperature and humidity in clothing when a person has performed light exercise. The environment of 20° C.×65% (RH) is a standard state approximating that of outside air temperature.

TABLE 4 Moisture Absorption/Desorption Property (Water Content Ratio) (%) Condition (RH) 40° C. × 90% 20° C. × 65% Time (h) 1 2 3 4 5 6 7 8 Inventive 8.8 10.8 11.8 12.4 8.6 8.1 8.0 7.9 Example B1 Comparative 9.5 11.2 12.1 12.6 9.1 8.5 8.3 8.3 Example B1

From Table 4, it can be understood that the moisture absorption/desorption property of the fiber material according to the inventive example is approximately the same as that of the fiber material of the comparative example. Stated otherwise, with the functional fiber according to the present embodiment, it is possible to impart the infrared radiation function and the deodorizing and antibacterial function without lowering the intrinsic moisture absorption/desorption property of the fiber material.

(Rapid Drying Ability)

Concerning the test specimen B1 from among the fiber materials according to the inventive example and the comparative example, a rapid drying ability test as described below was performed in order to evaluate the rapid drying ability thereof.

First, the weight (dry weight of the fiber material after drying) of the test specimen B1 according to the inventive example and the comparative example after drying at 105° C. for two hours was measured. Next, washing was carried out using a home electric washing machine VH-30S manufactured by Toshiba Corporation. More specifically, water and each of the measurement samples were inserted into a washing tub in a manner so that the measurement samples became 1 kg with respect to 30 L of water, or stated otherwise, so that the bath ratio was 1:30. At this time, the water temperature was set to 30° C. to 40° C. Further, the washing condition was set to a strong water flow condition, and washing was carried out one time for 30 minutes.

Thereafter, the weight after dehydration was performed for five minutes (weight of the fiber material after dehydration) was measured. Next, the test specimens were suspended and dried in a room at a temperature of 25° C.±1° C. and a humidity of 55%±5% (RH). At this time, the weight of the test specimens (weight of the fiber material during suspension drying) was measured with each elapse of a predetermined time period.

A difference between the weight of the fiber material after drying and the weight of the fiber material after dehydration is the weight (moisture weight after dehydration) of the moisture contained in the test specimens after dehydration. Therefore, the moisture content (%) of the test specimens when the suspension drying time is zero minutes is given by the formula, water content weight after dehydration (g)/weight of the fiber material after drying (g). Further, the moisture content (%) of the test specimens each time that suspension drying is performed is given by the formula (weight of fiber material during suspension drying (g)−weight of fiber material after drying (g))/weight of fiber material after drying (g). Moisture content ratios of test specimens of the inventive example and the comparative example calculated in this manner are shown in Table 5, together with the suspension drying time period.

TABLE 5 Suspension Drying Water Content Ratio (%) Time Period Inventive Comparative (minutes) Example Example B1 0 61.9 74.2 5 58.4 70.0 30 40.2 52.7 50 27.1 39.6 70 16.8 27.7 100 6.4 12.8 110 4.4 9.1

As can be understood from Table 5, at a point in time when the suspension drying time period was zero minutes, that is, in a state in which only dehydration was performed, the water content ratio of the fiber material according to the inventive example was lower than the water content ratio of the fiber material according to the comparative example. Therefore, it can be understood that, with the functional fiber according to the present embodiment, at a time of washing in water, swelling by absorption of water is suppressed.

Further, concerning the suspension drying time period required until the water content was decreased to 10%, with the fiber material according to the comparative example, the time period was 83.0 minutes, whereas with the fiber material according to the comparative example, the time period was 107.0 minutes. More specifically, the suspension drying time period of the fiber material according to the inventive example was shortened by 20% in comparison with the suspension drying time period of the fiber material according to the comparative example. Accordingly, the functional fiber according to the present embodiment is capable of enhancing a rapid drying ability in comparison with an untreated fiber material. 

1. A functional fiber having a fiber material imparted with an infrared radiation function and a deodorizing and antibacterial function, wherein: a silicone elastomer film containing aluminum oxide particles having an average particle diameter of 1 to 10 μm is affixed to at least a portion of a surface of the fiber material; and the silicone elastomer film contains as a principal component thereof polyoxyethylene alkyl ether having 12 to 15 carbon atoms, and has a siloxane skeleton.
 2. A method of manufacturing a functional fiber having a fiber material imparted with an infrared radiation function and a deodorizing and antibacterial function, comprising the steps of: immersing the fiber material in an aqueous dispersion liquid in which there are dispersed silicone elastomer particles containing as a principal component thereof polyoxyethylene alkyl ether having 12 to 15 carbon atoms, and having a siloxane skeleton, and aluminum oxide particles having an average particle diameter of 1 to 10 μm; and by a heating treatment, affixing to at least a portion of a surface of the fiber material the silicone elastomer in the form of a film in which the silicone elastomer particles are crosslinked, and containing the aluminum oxide particles. 